(a) Field of the Invention
The present invention relates to an etchant for a signal wire and a manufacturing method of a thin film transistor array panel using an etchant.
(b) Description of the Related Art
Liquid crystal displays (LCDs) are one of the most widely used flat panel displays. An LCD includes two panels provided with field-generating electrodes and a liquid crystal (LC) layer interposed therebetween. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer, which determines orientations of LC molecules in the LC layer to adjust polarization of incident light.
Among LCDs including field-generating electrodes on respective panels, a kind of LCDs provides a plurality of pixel electrodes arranged in a matrix at one panel and a common electrode covering an entire surface of the other panel. The image display of the LCD is accomplished by applying individual voltages to the respective pixel electrodes. For the application of the individual voltages, a plurality of three-terminal thin film transistors (TFTs) are connected to the respective pixel electrodes, and a plurality of gate lines transmitting signals for controlling the TFTs and a plurality of data lines transmitting voltages to be applied to the pixel electrodes are provided on the panel.
The panel for an LCD has a layered structure including several conductive layers and several insulating layers. The gate lines, the data lines, and the pixel electrodes are made from different conductive layers (referred to as “gate conductor,” “data conductor,” and “pixel conductor” hereinafter) preferably deposited in sequence and separated by insulating layers. A TFT includes three electrodes: a gate electrode made from the gate conductor and source and drain electrodes made from the data conductor. The source electrode and the drain electrode are connected by a semiconductor usually located thereunder, and the drain electrode is connected to the pixel electrode through a hole in an insulating layer.
The gate conductor and the data conductor are preferably made of Al containing metal such as Al and Al alloy having low resistivity for reducing the signal delay in the gate lines and the data lines. The data conductor also includes a refractory metal for good contact with the semiconductor. The pixel electrodes are usually made of transparent conductive material such as indium tin oxide (ITO) for both the field generation upon voltage application and the light transmission.
In the meantime, the conductors are patterned by dry etching or wet etching with an etchant. An etchant for patterning dual layers of Al (or Al—Nd alloy) and Mo is disclosed in Korean Patent Application Publication No. 2001-75932, an etchant for patterning triple layers of Mo, Al (or Al—Nd alloy), and Mo is disclosed in Korean Patent Application Publication Ser. No. 2001-91799, and an etchant for patterning a layer of ITO is disclosed in Korean Patent Application Publication Ser. No. 2002-33025.
Since different layers are etched using different etching conditions, the manufacturing process is complicated and the manufacturing cost is expensive.